In oil well production operations, relatively large quantities of water are frequently produced along with the oil. In some oil wells, water and other by-products can amount to as much as eighty to ninety percent of the total production yield. This is particularly true during the later stages of production.
Various methods have been employed for separating the oil from the water. For example, oil and water are typically pumped or otherwise flowed together to the surface where they are treated to separate the oil from the water. The water, after having been pumped to the well surface and separated, is disposed of by removal from the site or by pumping back into the well for injection into a disposal layer.
Downhole separation has also been used to separate the oil and water produced by a well. For example, hydroclones, dynamic mechanical systems that use centralized forces to separate fluids, and combinations of mechanical pumps and gravity separation have been used for achieving separation of production fluids into water and oil components. Hydrophilic and other semi-permeable membranes have been used in connection with submersible pumps for downhole separation.